<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <style>
        
    </style>
</head>
<body>
    <div class="box">
        <mark>内容</mark>
    </div>
    <input type="text" value="hello" class="ipt">
</body>
<script>

    var oBox = document.querySelector(".box")
    var oIpt = document.querySelector(".ipt")

    // console.log( oBox.innerHTML );
    // oBox.innerHTML =  "<em>hello div</em>";
    
    // console.log( oBox.innerText );
    // oBox.innerText =  "<em>hello div</em>";

    // console.log(oIpt.value);
    // oIpt.value = "这是输入框";

    
</script>
</html>